Septum Formation in the Green Alga Ulothrix Palusalsa (Chlorophyta, Ulvophyceae)

Abstract

The ultrastructure of cell division, with the emphasis on septum formation, is described in the ulvophycean green alga Ulothrix palusalsa Lokhorst. Septum formation involves a cleavage furrow which is initiated before the onset of mitosis. The development of the cleavage furrow is most pronounced at the final mitotic stages when it shows a serial arrangement of alternating thickened and flattened parts. Especially in the chloroplast region, a hoop of microtubules is sometimes associated with the leading edge of the cleavage furrow.